Zhu, Chen, Zhang, Zhang, Guo, Pang, Huang, Wang 2024 — Toxic and essential metals: metabolic interactions with the gut microbiota and health implications
This Frontiers in Nutrition review from the Zhejiang Center for Disease Control and Prevention synthesizes the metals-microbiota interaction literature across both toxic metals (Pb, Cd, As, Hg, Cr, Ni) and essential metals with toxicity at excess (Cu, Zn, Fe, Mn, Se). The review covers three principal axes: how metals modulate microbiota composition and diversity; how the microbiota modulates metal absorption, biotransformation, and excretion; and how these reciprocal interactions translate to metabolic and disease outcomes including inflammatory bowel disease, metabolic syndrome, neurodevelopmental disorders, and cardiovascular disease. The paper documents the metal-driven taxonomic shifts (Lactobacillus and Bifidobacterium decrease; Proteobacteria expansion) and the microbial-driven metal-speciation effects (gut microbial methylation of inorganic mercury and arsenic; siderophore-mediated metal scavenging).
Key conclusions
Toxic-metal-microbiota interactions are bidirectional: metals shape microbiota and microbiota shape metal fate. The toxic-metal exposure produces consistent microbiota signatures (loss of Lactobacillus and Bifidobacterium; rise in Proteobacteria including pathobionts) that overlap with dysbiosis signatures of multiple chronic-disease states. Microbial metal biotransformation can convert less-toxic forms to more-toxic forms (microbial mercury methylation in the gut producing methylmercury from inorganic mercury) or vice versa (microbial reduction of Cr-VI to Cr-III). The review proposes the gut microbiota as both a target of and a mediator of dietary heavy-metal toxicity, with implications for the relevance of microbiota-modulating interventions (probiotics, prebiotics, dietary fiber) in heavy-metal-exposed populations.
Implications
- Certification: Background context for the broader public-health case for tight HMTc thresholds. The microbiota-mediator framing reinforces that “internal dose” of a heavy metal depends on gut microbial composition, which complicates simple intake-to-effect relationships and supports precautionary certification approaches.
- Microbiome: Comprehensive review for the metals-microbiota-health-outcomes triangulation. Crosswalks to WikiBiome for the multi-metal review of microbiota interactions.
- Courses: Useful for teaching the microbiota-mediator framework in dietary toxicology.